A study for the mechanism of hematopoietic regulation by bone marrow stromal cells

正常造血的特征在于造血干细胞与形成其中发生血细胞产生的微环境部分的细胞和分子之间的平衡相互作用。这反过来表明，这种微环境的某些元素的改变可能导致血细胞的异常产生。骨髓基质细胞是骨髓间充质细胞的异质集合，在骨髓培养中作为粘附层生长，是微环境的重要组成部分。本研究从骨髓增生异常综合征（MDS）难治性贫血（RA）患者骨髓基质细胞（LS 801）出发，通过重组腺病毒载体介导SV40早期基因，建立了一株克隆化的骨髓基质细胞系。LS 801可诱导共培养体系中的造血细胞发生凋亡。2. LS 801通过产生扩散因子和直接细胞相互作用诱导造血细胞发生凋亡。从LS 801的培养基中分离得到一种超分子低聚物环状聚乳酸。发现该寡聚体诱导造血细胞的凋亡变化。其作用机制尚不清楚，但可抑制造血细胞糖酵解酶磷酸果糖激酶和己糖激酶的活性。3. MDS患者骨髓基质细胞通过产生TNFα诱导造血细胞凋亡。结果表明，维生素K_2可抑制基质细胞产生TNFα，刺激造血细胞的增殖和分化，提示基质细胞对造血细胞的增殖和分化具有促进和抑制作用。

Normal hematopoiesis is characterized by a balanced interplay between hematopoietic stem cells and the cells and molecules that form the portion of the microenvironment in which blood cell production takes place. This in turn suggests that alterations in some of the elements of this microenvironment may result in abnormal production of blood cells. Bone marrow stromal cells, a heterogeneous collection of mesenchymal cells that grow as an adherent layer in bone marrow culture, are an essential component of the microenvironment. In this study, the hematopoietic regulatory mechanisms of stromal cells were investigated in vitro.1.A cloned stromal cell line (LS801) was established from an myelodysplastic syndrome(MDS) refractory anemia(RA) patient by introducing recombinant SV40-adenovirus vector containing the SV40 early gene. LS801 induced an apoptotic change in hematopoietic cells in a coculture system.2.LS801 was shown that induced an apoptotic change of hematopoietic cells by producing diffusible factor(s) and via direct cellular interactions. A supramolecular oligomer, cyclic polylactate was isolated from the culture medium of LS801. This oligomer was found to induce apoptotic change in hematopoietic cells. The mechanism responsible for this action remains unclear, however, the activities of glycolytic enzymes, phosphofructokinase and hexokinase, of hematopoietic cells were suppressed by treatment with this oligomer,3.In some stromal cells originated from MDS patients induced apoptotic change of hematopoietic cells by producing TNFα. We found that the treatment with vitamin K2 suppressed the production of TNFα from these stromal cells, and hematopoiesis in culture with these stromal cells was stimulated.All these findings suggest that stromal cells possess both stimulatory and inhibitory action for the proliferation and differentiation of hematopoietic cells.